Magnetic resonance of charge carrier (so called polaron) spin states in thin solid films made of π-conjugated polymers can be observed through the measurement of charge carrier recombination currents in diode devices that allow for both electron and hole polaron injection.
Such electrical detection of magnetic resonance (EDMR) is significantly more sensitive than inductively detected magnetic resonance as the resonantly measured sample current is only weakly dependent of the polaron ensemble magnetization, and thus, it is not directly dependent on the applied temperature, the magnetic field, or the sample volume. For this reason EDMR on polymer-thin film diodes has been used in the past for magnetic resonance based absolute magnetometry of mid to low magnetic field domains. Furthermore, EDMR spectroscopy at low static field B0 and high driving field B1 has become of fundamental interest for the exploration of nonlinear magnetic field phenomena.